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排序方式: 共有314条查询结果,搜索用时 15 毫秒
61.
Takeshi Yoshida Lanxi Song Yun Bai Fumi Kinose Jiannong Li Kim C. Ohaegbulam Teresita Mu?oz-Antonia Xiaotao Qu Steven Eschrich Hidetaka Uramoto Fumihiro Tanaka Patrick Nasarre Robert M. Gemmill Jo?lle Roche Harry A. Drabkin Eric B. Haura 《PloS one》2016,11(1)
Epithelial-mesenchymal transition (EMT) is one mechanism of acquired resistance to inhibitors of the epidermal growth factor receptor-tyrosine kinases (EGFR-TKIs) in non-small cell lung cancer (NSCLC). The precise mechanisms of EMT-related acquired resistance to EGFR-TKIs in NSCLC remain unclear. We generated erlotinib-resistant HCC4006 cells (HCC4006ER) by chronic exposure of EGFR-mutant HCC4006 cells to increasing concentrations of erlotinib. HCC4006ER cells acquired an EMT phenotype and activation of the TGF-β/SMAD pathway, while lacking both T790M secondary EGFR mutation and MET gene amplification. We employed gene expression microarrays in HCC4006 and HCC4006ER cells to better understand the mechanism of acquired EGFR-TKI resistance with EMT. At the mRNA level, ZEB1 (TCF8), a known regulator of EMT, was >20-fold higher in HCC4006ER cells than in HCC4006 cells, and increased ZEB1 protein level was also detected. Furthermore, numerous ZEB1 responsive genes, such as CDH1 (E-cadherin), ST14, and vimentin, were coordinately regulated along with increased ZEB1 in HCC4006ER cells. We also identified ZEB1 overexpression and an EMT phenotype in several NSCLC cells and human NSCLC samples with acquired EGFR-TKI resistance. Short-interfering RNA against ZEB1 reversed the EMT phenotype and, importantly, restored erlotinib sensitivity in HCC4006ER cells. The level of micro-RNA-200c, which can negatively regulate ZEB1, was significantly reduced in HCC4006ER cells. Our results suggest that increased ZEB1 can drive EMT-related acquired resistance to EGFR-TKIs in NSCLC. Attempts should be made to explore targeting ZEB1 to resensitize TKI-resistant tumors. 相似文献
62.
Masaki Kobayashi Eiji Yamato Koji Tanabe Fumi Tashiro Satsuki Miyazaki Jun-ichi Miyazaki 《PloS one》2016,11(3)
Elucidating the regulation of glucose-stimulated insulin secretion (GSIS) in pancreatic β cells is important for understanding and treating diabetes. The pancreatic β cell line, MIN6, retains GSIS but gradually loses it in long-term culture. The MIN6 subclone, MIN6c4, exhibits well-regulated GSIS even after prolonged culture. We previously used DNA microarray analysis to compare gene expression in the parental MIN6 cells and MIN6c4 cells and identified several differentially regulated genes that may be involved in maintaining GSIS. Here we investigated the potential roles of six of these genes in GSIS: Tmem59l (Transmembrane protein 59 like), Scgn (Secretagogin), Gucy2c (Guanylate cyclase 2c), Slc29a4 (Solute carrier family 29, member 4), Cdhr1 (Cadherin-related family member 1), and Celsr2 (Cadherin EGF LAG seven-pass G-type receptor 2). These genes were knocked down in MIN6c4 cells using lentivirus vectors expressing gene-specific short hairpin RNAs (shRNAs), and the effects of the knockdown on insulin expression and secretion were analyzed. Suppression of Tmem59l, Scgn, and Gucy2c expression resulted in significantly decreased glucose- and/or KCl-stimulated insulin secretion from MIN6c4 cells, while the suppression of Slc29a4 expression resulted in increased insulin secretion. Tmem59l overexpression rescued the phenotype of the Tmem59l knockdown MIN6c4 cells, and immunostaining analysis indicated that the TMEM59L protein colocalized with insulin and GM130, a Golgi complex marker, in MIN6 cells. Collectively, our findings suggested that the proteins encoded by Tmem59l, Scgn, Gucy2c, and Slc29a4 play important roles in regulating GSIS. Detailed studies of these proteins and their functions are expected to provide new insights into the molecular mechanisms involved in insulin secretion. 相似文献
63.
Stripping of conifer tree bark by Asian black bears (Ursus thibetanus) has been observed in parts of Japan. To identify and characterize the bears exhibiting this behavior, we performed a genetic
analysis using DNA extracted from the hairs left on damaged trees. We analyzed 219 samples of bear hair collected from damaged
trees at 33 sites and 64 tissue samples from captured bears as controls by using ten microsatellite DNA loci, ca. 706 bp of
the mitochondrial DNA d-loop region, and the amelogenin locus. Sixteen bears were identified; some of them had damaged trees at more than one site.
bark-stripping and the captured bears. Spatial autocorrelation analysis for increasing distance class revealed a significantly
positive genetic correlation coefficient within 40 km among the bark-stripping bears (P < 0.05). Relatedness among the bark-stripping bears was higher than among the captured bears when the distance between bears
was within 25 km. We concluded that bark-stripping behavior is associated with relatedness. 相似文献
64.
Mitsuhiro Uchida Fumi Ito Toshiyuki Tsuchiya Yoko Shoji Toru Kurosawa 《Experimental Animals》2015,64(4):333-341
Beagle dogs have long been employed in toxicology studies and as skin disease models.
Compared with other experimental animal species, they are known to be susceptible to skin
responses, such as rashes, from exposure to various chemical compounds. Here, a unique dog
phenotype was identified that showed no skin response to compound 48/80, a mast cell
degranulating agent. Although the skin responses to intradermal injection of
polyoxyethylene castor oil derivative (HCO-60, a nonionic detergent), histamine
dihydrochloride, concanavalin A (IgE receptor-mediated stimuli), or calcium ionophore
were comparable in wild-type (WT) dogs and these nonresponder (NR) dogs, only the
response to compound 48/80 was entirely absent from NR dogs. The skin mast cell density
and histamine content per mast cell were histologically comparable between WT and NR dogs.
By checking for skin responses to compound 48/80, NR dogs were found to exist at the
proportion of 17–20% among four animal breeders. From retrospective analysis of in-house
breeding histories, the NR phenotype appears to conform to the Mendelian pattern of
recessive inheritance. The standard skin response in WT dogs developed at 2–4 months of
age. In conclusion, this unique phenotype, typified by insensitivity in the compound
48/80-induced degranulation pathway in mast cells, has been widely retained by recessive
inheritance in beagle dogs among general experimental animal breeders. The knowledge
concerning this phenotype could lead to better utilization of dogs in studies and aid in
model development. A23187相似文献
65.
Tsubokawa D Goso Y Nakamura T Maruyama H Yatabe F Kurihara M Ichikawa T Ishihara K 《Experimental parasitology》2012,130(3):209-217
The intestinal parasitic nematode Nippostrongylus brasiliensis is expelled rapidly from the rat in reinfection challenge compared with that of the primary infection owing to the host defense mechanisms raised against the pre-intestinal- and intestinal-stage larvae. We examined the relationship between the mucin alterations in airway and jejunal mucosae and the worm expulsion after third-stage larva reinfection. When rats had been inoculated with fourth-stage larvae and immunized with only the intestinal-stage worms for more than 8 days, the challenge larvae were expelled during the intestinal stage along with a rapid increase of the specific sialomucin in jejunal mucosa, without any effect on the bronchial mucus. When rats had been infected with third-stage larvae and immunized with only the pre-intestinal stage larvae by killing with antihelminthic, the challenge larvae were rejected during the pre-intestinal stage along with marked goblet cell hyperplasia and Muc5AC mucin hyperproduction on the bronchial mucosa, but not as a result of jejunal mucin alteration. Taking these finding together, immunization with pre-intestinal- and intestinal-stage worms independently increases the airway and intestinal goblet cell mucins, respectively, and in both cases, the mucin alterations may contribute to rapid worm expulsion upon reinfection. 相似文献
66.
Beluzić R Cuk M Pavkov T Fumić K Barić I Mudd SH Jurak I Vugrek O 《The Biochemical journal》2006,400(2):245-253
Recently, we have described the first human case of AdoHcyase (S-adenosylhomocysteine hydrolase) deficiency. Two point mutations in the AdoHcyase gene, the missense mutation p.Y143C (AdoHcyase in which Tyr143 is replaced by cysteine) and the truncation mutation p.W112stop (AdoHcyase in which Trp112 is replaced by opal stop codon) were identified [Bari?, Fumi?, Glenn, Cuk, Schulze, Finkelstein, James, Mejaski-Bosnjak, Pazanin, Pogribny et al. (2004) Proc. Natl. Acad. Sci. U.S.A. 101, 4234-4239]. To elucidate the molecular and catalytic properties of AdoHcyase, we have made recombinant wild-type and mutant p.Y143C (AdoHcyase in which Tyr143 is replaced by cysteine) enzymes for a comparative analysis. The catalytic rates of p.Y143C protein in the directions of S-adenosylhomocysteine synthesis or hydrolysis are decreased from 65% to 75%. Further, the oxidation states of coenzyme NAD differ between mutant and wild-type protein, with an increased NADH accumulation in the mutant p.Y143C enzyme of 88% NADH (wild-type contains 18% NADH). Quantitative binding of NAD is not affected. Native polyacrylamide gel electrophoresis showed, that mutant p.Y143C subunits are able to form the tetrameric complex as is the wild-type enzyme. CD analysis showed that the p.Y143C mutation renders the recombinant protein thermosensitive, with an unfolding temperature significantly reduced by 7 degrees C compared with wild-type protein. Change of Glu115 to lysine in wild-type protein causes a change in thermosensitivity almost identical with that found in the p.Y143C enzyme, indicating that the thermosensitivity is due to a missing hydrogen bond between Tyr143 and Glu115. We emphasize involvement of this particular hydrogen bond for subunit folding and/or holoenyzme stability. In summary, a single mutation in the AdoHcyase affecting both the oxidation state of bound co-factor NAD and enzyme stability is present in a human with AdoHcyase deficiency. 相似文献
67.
Urano F Hayashi N Arisaka F Kurita H Murata S Ichinose H 《Journal of biochemistry》2006,139(4):625-635
Tyrosine hydroxylase (TH), an iron-containing enzyme, catalyzes the first and rate-limiting step of catecholamine biosynthesis, and requires tetrahydrobiopterin (BH4) as a cofactor. We found that preincubation of recombinant human TH with BH4 results in the irreversible inactivation of the enzyme at a concentration far less than the Km value toward BH4 in spite of its cofactor role, whereas oxidized biopterin, which has no cofactor activity, does not affect the enzyme activity. We show that TH is inactivated by BH4 in competition with the binding of dopamine. The sequential addition of BH4 to TH results in a gradual decrease in the intensity of the fluorescence and CD spectra without changing their overall profiles. Sedimentation velocity analysis demonstrated an association of TH molecules with each other in the presence of BH4, and studies using gel-permeation chromatography, turbidity measurements, and transmission electron microscopy demonstrated the formation of amorphous aggregates with large molecular weights following the association of the TH proteins. These results suggest that BH4 not only acts as a cofactor, but also accelerates the aggregation of TH. We propose a novel mechanism for regulating the amount of TH protein, and discuss its physiological significance. 相似文献
68.
Synchronization is a powerful technique for understanding cell cycle events. Here, we describe the procedure for synchronizing tobacco bright yellow 2 (BY-2) cell line, with which an exceptionally high level of synchrony can be achieved. It basically relies on an "arrest-and-release" strategy using aphidicolin, an inhibitor of DNA replication, and propyzamide, a plant-microtubule disruptant. In a single-step process using aphidicolin alone, a cell population with about 70% of the cells at mitosis can be achieved, whereas by a two-step method using the two inhibitors sequentially, the level of synchrony can reach over 90%. The method of choice depends not only on the peak mitotic cell proportion but also on the cell cycle stage that is targeted for analysis. Both procedures take about 1.5 days, and cell cycle progression can be observed from the S phase to the next G1 phase at about 12 h after a 24 h-period treatment with aphidicolin. 相似文献
69.
Mori I Goshima F Watanabe D Ito H Koide N Yoshida T Liu B Kimura Y Yokochi T Nishiyama Y 《Microbes and infection / Institut Pasteur》2006,8(7):1806-1812
A role for the US3 protein kinase of herpes simplex virus (HSV) in regulating virus-induced neuronal apoptosis was investigated in an experimental mouse system, in which wild-type HSV invades the central nervous system (CNS) via the olfactory and vomeronasal systems upon intranasal infection. Wild-type HSV-2 strain 186 infected a fraction of olfactory and vomeronasal chemosensory neurons without inducing apoptosis and was transmitted to the CNS, precipitating lethal encephalitis. In sharp contrast, an US3-disrupted mutant, L1BR1, induced neuronal apoptosis in these peripheral conduits upon infection, blocking viral transmission to the CNS and causing no signs of disease. An US3-repaired mutant, L1B(-)11, behaved similarly to the wild-type virus. Only 5 p.f.u. of L1BR1 was sufficient to compromise mice when the mutant virus was introduced directly into the olfactory bulb, a viral entry site of the CNS. These results suggest that the US3 protein kinase of HSV regulates virus-induced neuronal apoptosis in peripheral conduits and determines the neuroinvasive phenotype of HSV. Furthermore, virus-induced neuronal apoptosis of peripheral nervous system cells may be a protective host response that blocks viral transmission to the CNS. 相似文献
70.